Light guide with multi-directional optics

ABSTRACT

A light guide is provided having an elongate body extending in a longitudinal direction having a light transmission portion with a forward light exit surface and a reflective track extending opposite the light exit surface. A plurality of reflective elements are formed along the reflective track and spaced apart in the longitudinal direction. Each reflective element has a center segment and a pair of edge segments each oriented at a spread angle from the center segment toward the light transmission portion, thereby increasing a spread of light output in a horizontal direction from the light transmission portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application Ser.No. 63/337,604 filed May 2, 2022, the disclosure of which is herebyincorporated in its entirety by reference herein.

TECHNICAL FIELD

The present application relates to light guides suitable for use inlamps, such as vehicle lamps.

BACKGROUND

Vehicle lamps may have a light source and a light guide to receive lightemitted from the light source at an end surface thereof. The light guidereceives the light emitted from the light source and guides the lightthrough the light guide via total internal reflection and then directsthe light to be emitted toward the front of the vehicle through an exitsurface extending in a direction in which the light guide extends. Inthe light guide, a number of reflective elements are formed in a surfaceto reflect the light toward the exit surface. One example of a lightguide is U.S. Pat. No. 10,876,703 by Koito.

SUMMARY

According to at least one embodiment, a lamp comprises a light guidehaving multi directional optics.

According to at least one embodiment, a lamp comprises a light guidehaving an optics portion having multiple surfaces offset at anglerelative to a longitudinal axis of the light guide.

According to at least one embodiment, a vehicle lamp is provided havinga lamp housing having an opening. A light-transmissive outer cover ispositioned to cover the opening in the lamp housing and defining a lampchamber therebetween. A light guide is arranged in the lamp chamberhaving an elongate body extending in a longitudinal direction. Theelongate body has a light transmission portion and a reflective trackextending from the light transmission portion. A light source ispositioned adjacent at least one end of the light guide. The light guidehas a plurality of reflective elements formed along the reflective trackand spaced apart in the longitudinal direction, each reflective elementhaving a center segment and a pair of edge segments, each oriented at aspread angle from the center segment toward the light transmissionportion, thereby increasing a spread of light output from in a directiongenerally perpendicular to the longitudinal direction.

In another embodiment, the light guide is arranged generally verticallywithin the lamp chamber, and where the plurality of reflective elementsdefine a light output pattern being generally horizontal andperpendicular to the longitudinal direction.

In another embodiment, the lamp comprises one of a headlamp or daytimerunning lamp.

In another embodiment, the edge segments have an edge prism defined by atriangle prism oriented at the spread angle from the center segmenttoward the light transmission portion, whereby each one of the edgesegments positioned on opposite sides of the center segment increase indepth as the edge segment extends away from the center segment.

In another embodiment, a prism angle of each of the reflective elementsvaries along the length of the elongate body as the orientation of thelongitudinal direction varies within the lamp chamber.

According to at least one embodiment, a light guide is provided havingan elongate body extending in a longitudinal direction and having across section transverse to the longitudinal direction having a lighttransmission portion being generally circular and a reflective trackprotruding from the light transmission portion. A plurality ofreflective elements are formed along the reflective track and are spacedapart in the longitudinal direction. Each reflective element has acenter segment and a pair of edge segments. Each one of the edgesegments is positioned on opposite sides of the center segment andincreases in depth as the edge segment extends away from the centersegment.

In another embodiment, the reflective elements are defined as atriangular prism, wherein the triangle prism of the center segment has aconstant depth.

In another embodiment, the edge segments are oriented at a spread anglefrom the center segment toward the light transmission portion, therebyincreasing a spread of light output in a horizontal direction from thelight transmission portion.

In another embodiment, each edge prism has a front prism surface and aback prism surface, the front and back prism surfaces increasing in sizeas the edge segment extends away from the center segment.

In another embodiment, the light transmission portion has a generallycircular cross section.

According to at least one embodiment, light guide is provided having anelongate body extending in a longitudinal direction having a lighttransmission portion with a forward light exit surface and a reflectivetrack extending from the light transmission portion opposite the lightexit surface. A plurality of reflective elements are formed along thereflective track and are spaced apart in the longitudinal direction.Each reflective element has a center segment and a pair of edge segmentseach oriented at a spread angle from the center segment toward the lighttransmission portion, thereby increasing a spread of light output in ahorizontal direction from the light transmission portion.

In another embodiment, the reflective track extends in at least one arearward direction to form a protrusion or extends in a forwarddirection to form a notch.

In another embodiment, the reflective elements are generally symmetricabout a plane parallel to a central longitudinal axis of the body andthe edge segments are mirror images about the central longitudinal axis.

In another embodiment, each edge prism has a front prism surface and aback prism surface, the front and back prism surfaces increasing in sizeas the edge segment extends away from the center segment.

In another embodiment, the triangle prism of center segment a constantdepth and having a front prism surface and a back prism surface beinggenerally equal.

In another embodiment, the spread angle is in the range of 2-degrees to20-degrees. In another embodiment, the spread angle is in the range of5-degrees to 15-degrees.

In another embodiment, a prism angle of the center segment is generallythe same as a prism angle of the edge segments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a vehicle lamp having a lightguide according to one embodiment of the present application.

FIG. 2 is a side perspective view of the lamp in FIG. 1 .

FIG. 3 is a perspective view of the light guide in FIGS. 1-2 accordingto one aspect of the present application.

FIG. 4 is a section-view of the light guide in FIG. 3 along sectionlines 4-4 and including light ray traces according to one aspect of thepresent application.

FIG. 5 is an iso-plot of the light output pattern of the light guideaccording to one aspect of the application.

FIG. 6 is perspective view of an example of a light guide based oncurrent technology.

FIG. 7 is a section-view of the light guide in FIG. 8 along sectionlines 9-9 and including light ray traces.

FIG. 8 is a detailed view of a portion of the light guide according toone aspect of the present application.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

Generally vertical light guides naturally lead to vertical spread butlimited horizontal spread of the light output. This is especiallyproblematic when trying to meet requirements for vehicle lamps such asheadlamps or daytime running lamps or lighting requirements in somecountries.

FIGS. 1-2 illustrate a vehicle lamp 10 having a light guide 40 with aplurality of reflective optics 42 for increasing the spread of the lightoutput and increasing efficiency of the lamp along portions of the lightguide 40 where styling and/or packaging require at least a portion 90 ofthe light guide 40 to be oriented in the upright direction. The uprightportion 90 may be generally vertical in the Y-direction, and may varyfrom the vertical direction while still extending generally vertical, asshown in FIGS. 1-2 .

According to one embodiment of the present application, the light guide40 includes multi-directional optics 42. The multi-directional optics 42formed along the light guide increase the horizontal spread, and alsoincrease the overall efficiency of the light guide. Themulti-directional optics may also reduce cost by reducing the amount ofrequired input flux and reducing the requirements of the light sourcedue to the improved efficiency and control of the light output pattern.

FIG. 1 is a schematic front perspective/front view of the vehicle lamp10 according to one embodiment. FIG. 2 is a side/perspective view of thevehicle lamp. The vehicle lamp 10 may be a headlamp or daytime runninglamp mounted in a front portion of a vehicle, for example. However, thevehicle lamp 10 and light guide 40 may be used in other vehicle lampapplications such as a turn signal lamp, rear lamp, or other vehiclesuitable vehicle lamps. The vehicle lamp 10 includes a lamp housing 12defining a front opening and a light-transmissive outer cover 14 thatcovers the opening in the lamp housing 12 and forms a lamp chamber 16therebetween. A light source 18 is disposed at a distal end of theelongate body of the light guide. The light source 18 and the lightguide 40 are disposed in the lamp chamber 16. The light source 18 andthe light guide 40 may be each fixed to the lamp housing 12 or may bemounted to other components of the lamp such as other reflectors, bezelsor features of the lamp 10. In another embodiment, the lamp 10 may havea light source 18 disposed at both ends of the elongate body of thelight guide 40.

The light source 18 is a light-emitting diode (LED), for example.Alternatively, the light source 108 may be a laser diode (LD), anothersemiconductor light-emitting element such as an organic or inorganicelectroluminescent (EL) element, an incandescent lamp, a halogen lamp, adischarge lamp, or other suitable light source.

As shown in more detail in FIG. 3 , the light guide 40 is a conduit madeof transparent material, such as glass or plastic, which is capable ofchanneling light from one end to the other through total internalreflection (TIR). The light guide 40 has an elongate body extending in alongitudinal direction L, whereas the longitudinal direction isgenerally parallel to the direction of light propagated via TIR withinthe light guide 40. The elongated light guide 40 is formed of a lighttransmission portion 44 and a reflective track 46 extending in thelongitudinal direction along the length of the light guide 40. As shownin FIGS. 1-2 , the orientation of the light guide 40 may vary along thelength.

FIG. 4 shows a cross-section taken along line 4-4 (FIG. 3 ) which istransverse to the longitudinal direction L. As shown in FIG. 4 , thelight transmission portion 44 has a generally circular cross-section andthe reflective track 46 protrudes rearward from the light transmissionportion 44. Light is emitted from the light guide 40 in the longitudinaldirection L and is directed forward through a forward exit surface 48 bya plurality of reflective elements 50 are formed along the reflectivetrack 46. However, the transmission portion 44 may have other suitablecross-section shapes that allow for light propagation from the lightsource 18 through total internal reflection (TIR) along the longitudinaldirection L of the light guide 40. In another embodiment, the reflectivetrack 46 may extend inward into the transmission portion 44, therebyforming a notch.

The plurality of reflective elements 50 are formed along the reflectivetrack 46. The reflective elements 50 are spaced apart in thelongitudinal direction. Each reflective element 50 has a center segment52 and a pair of edge segments 54. The edge segments 54 are positionedon opposite sides of the center segment 52. The edge segments 54 mayeach have generally the same dimension. However, each of the edgesegments 54 may have different dimensions or configurations depending onthe desired light output pattern.

As shown in more detail in FIG. 8 , the reflective elements 50 areformed as generally triangular prisms. The reflective elements 50 have afront prism surface 56 and a back prism surface 58. The center segment52 is formed as a triangular prism having a constant depth. In oneexample, front prism surface 56 and the back prism surface 58 may beasymmetric and be oriented at different angles relative to the directionof light. In another embodiment, the triangular prisms of the reflectiveelements 50 are symmetric about a plane perpendicular to thelongitudinal direction surface being generally equal.

The dimensions and orientations of the front prism surface 56 and theback prism surface 58 may vary along the length of the light guide 40 asthe orientation of the light guide 40 varies relative to a vertical andhorizontal orientations, or the desired light output direction, or otherlamp variable.

The edge segments 54 are also shaped as triangular prisms and increasein depth as the edge segment extends away from the center segment 52.Along the edge segments 54, the front prism surface 56 and back prismsurface 58 increase in size as the edge segment 54 extends away from thecenter segment 52. For example, the center segment 52 may have aconstant depth of 0.17 mm and the edge segment 54 increases in depth to0.22 mm. Other dimensions may be suitable based on the desired lightoutput pattern. The dimensions of the center segment 52 and edge segment54 may also vary along the length of the light guide 40 as theorientation of the light guide 40 varies relative to a vertical andhorizontal orientations, or the desired light output direction, or otherlamp variable. The reflective elements 50 may be generally symmetricabout a plane parallel to the central longitudinal axis such that theedge segments 54 are mirror images of each other.

In this example, the light guide 40 may have a light transmissionportion 44 having a diameter of approximately 7-9 millimeters (mm) and areflective track that extends approximately 0.5-1 mm. In anotherembodiment, the light transmission portion 44 may have a diameter ofapproximately 6-12 mm and a reflective track that extends approximately0.3-4 mm. The transmission portion 44 and reflective track 46 may haveany suitable dimensions depending on the application, outputrequirements, styling or other factors.

The prism angle B of each of the reflective element surfaces may alsovary along the length of the light guide 40. The prism angle of thecenter segment 52 is generally the same as a prism angle of the edgesegments 54. The prism angle B between the front and back prism surfaces56, 58 may be in the range of 15-degrees to 75-degrees. In anotherembodiment, the prism angle B of the center segment 52 is different thana prism angle B of the edge segments 54.

The edge segments 54 have an edge prism defined by a triangle prismoriented at a spread angle A from the center segment 52 toward the lighttransmission portion 44, thereby increasing the spread of light outputin a horizontal direction from the light transmission portion. Thespread angle A may be in the range of 2-degrees to 20-degrees. While thespread angle A may be optimized for different output light patterns, ata spread angle greater than 20-degree, the light pattern may begin toseparate.

In another embodiment, the spread angle is in the range of 5-degrees to15-degrees. The spread angle A may also vary along the longitudinallength of the light guide 40. In another example, the multi-surfacededge segments 54 may be rotated at an angle A of approximately10-degrees.

As shown in FIGS. 6-7 , standard light guides 80 use a single flat tracksurface 82 with the prism optics 84. The conventional method ofincreasing horizontal spread is to widen the optics track 82, whichleads to reduced efficiency.

The light guide 40 with multi-directional optics creates light pattern70 with increased perpendicular spread, as shown in FIGS. 4-5 . Thelight pattern 70 may include a central region 72 and hot spots 74 thatextend the horizontal spread for light guides that are oriented in theupright direction or extending generally vertically in the Y-direction.The light pattern 70 not only increases horizontal spread to meetstandards, the output also increases in efficiency. In this example,efficiency increased by 11%. The horizontal width and efficiency areincreased by having more control over the spread of the light. The raytraces in FIG. 4 illustrate the levels of spread with the light guidehaving multi-directional optics, compared to prior solutions (FIG. 7 ).

The multi-directional optics 42 increase the spread of the light patternin a direction perpendicular to the longitudinal direction L of thelight guide 40. In the example shown in FIGS. 1-2 the reflectiveelements 50 are formed primarily on the upright portion 90 of the lightguide 40 oriented vertically, thereby increasing the horizontal lightspread, as shown in FIGS. 4-5 . The horizontal portion 92 of the lightguide 40 that extends generally in the horizontal X-direction may notinclude multi-directional optics 42 and may only have standard optics84, for example. The dimensions of the multi-directional optics 42,including the reflective elements 50, center segments 52, edge segments54 and angles A, B, may vary as the light guide 40 orientation andcurvature changes. This may be particularly evident along a curvedportion 94, although the dimensions of the multi-directional optics 42may also vary along the length of the upright portion 90.

Multi-directional optics are a unique way to improve light guidepattern, performance, and efficiency by increasing the perpendicularspread and having more control of the optics. Increased efficiency willreduce cost by decreasing design time and required input flux.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A vehicle lamp, comprising: a lamp housing havingan opening; a light-transmissive outer cover that covers the opening inthe lamp housing and defining a lamp chamber therebetween; a light guidearranged in the lamp chamber having an elongate body extending in alongitudinal direction, the elongate body having a light transmissionportion and a reflective track protruding from the light transmissionportion; and a light source positioned adjacent at least one end of thelight guide, wherein the light guide has a plurality of reflectiveelements formed along the reflective track and spaced apart in thelongitudinal direction, each reflective element having a center segmentand a pair of edge segments, each oriented at a spread angle from thecenter segment toward the light transmission portion, thereby increasinga spread of light output from in a direction generally perpendicular tothe longitudinal direction.
 2. The vehicle lamp of claim 1, wherein thelight guide is arranged generally vertically within the lamp chamber,and where the plurality of reflective elements define a light outputpattern being generally horizontal and perpendicular to the longitudinaldirection.
 3. The vehicle lamp of claim 1, wherein the lamp comprisesone of a headlamp or daytime running lamp.
 4. The vehicle lamp of claim1, wherein the edge segments have an edge prism defined by a triangleprism oriented at the spread angle from the center segment toward thelight transmission portion, whereby each one of the edge segmentspositioned on opposite sides of the center segment increase in depth asthe edge segment extends away from the center segment.
 5. The vehiclelamp of claim 1, wherein a prism angle of each of the reflectiveelements varies along the length of the elongate body as the orientationof the longitudinal direction varies within the lamp chamber.
 6. A lightguide comprising: an elongate body extending in a longitudinal directionand having a cross section transverse to the longitudinal directionhaving a light transmission portion being generally circular and areflective track protruding from the light transmission portion; and aplurality of reflective elements formed along the reflective track andspaced apart in the longitudinal direction, each reflective elementhaving a center segment and a pair of edge segments, each one of theedge segments positioned on opposite sides of the center segment andincreasing in depth as the edge segment extends away from the centersegment.
 7. The light guide according to claim 6, wherein the reflectiveelements are defined as a triangular prism, wherein the triangle prismof the center segment has a constant depth.
 8. The light guide accordingto claim 7, wherein the edge segments are oriented at a spread anglefrom the center segment toward the light transmission portion, therebyincreasing a spread of light output in a horizontal direction from thelight transmission portion.
 9. The light guide according to claim 8,wherein each edge prism has a front prism surface and a back prismsurface, the front and back prism surfaces increasing in size as theedge segment extends away from the center segment.
 10. The light guideaccording to claim 6, wherein reflective track protrudes rearward fromthe transmission portion and has a generally rectangular cross-section.11. A light guide comprising: an elongate body extending in alongitudinal direction having a light transmission portion with aforward light exit surface and a reflective track extending from thelight transmission portion opposite the light exit surface; and aplurality of reflective elements formed along the reflective track andspaced apart in the longitudinal direction, each reflective elementhaving a center segment and a pair of edge segments each oriented at aspread angle from the center segment toward the light transmissionportion, thereby increasing a spread of light output in a horizontaldirection from the light transmission portion.
 12. The light guideaccording to claim 11, wherein the edge segments increase in depth asthe edge segment extends away from the center segment at the spreadangle.
 13. The light guide according to claim 11, wherein the lighttransmission portion has a generally circular cross section, wherein thereflective track extending in at least one of a rearward direction toform a protrusion or extending in a forward direction to form a notch.14. The light guide according to claim 11, wherein the reflectiveelements are generally symmetric about a plane parallel to a centrallongitudinal axis of the body and the edge segments are mirror imagesabout the central longitudinal axis.
 15. The light guide according toclaim 11, wherein the center segment and the edge segments are definedas a triangular prisms.
 16. The light guide according to claim 15,wherein each edge prism has a front prism surface and a back prismsurface, the front and back prism surfaces increasing in size as theedge segment extends away from the center segment.
 17. The light guideaccording to claim 15, wherein the triangle prism of the center segmenthas a constant depth and having a front prism surface and a back prismsurface being generally equal.
 18. The light guide according to claim12, wherein the spread angle is in the range of 2-degrees to 20-degrees.19. The light guide according to claim 12, wherein the spread angle isin the range of 5-degrees to 15-degrees.
 20. The light guide accordingto claim 12, wherein a prism angle of the center segment is generallythe same as a prism angle of the edge segments.